Quantum key distribution (QKD) enables generation of secured shared randomness between two communicating parties, which facilitates secure communications between the parties. Continuous-variable quantum key distribution (CV-QKD) is a method of QKD that encodes data on phase and amplitude quadratures of a continuous optical signal. When communicating using CV-QKD, interferometric detection is used to measure the phase or amplitude quadratures of a received signal. Conventional CV-QKD systems rely on a transmitter transmitting a local oscillator signal at a power that is orders of magnitude higher than a power of the data signal to be measured; this power discrepancy improves performance of the aforementioned interferometric detection. When transmitting the local oscillator, the transmitter physically separates the local oscillator and data signal prior to encoding the data signal. Separation of the local oscillator and data signal is undertaken to avoid contamination of the low-power data signal by the high-power local oscillator.